The present invention relates to a respiratory suction catheter assembly with an improved mechanism for cleaning the tip of the catheter without drawing an excessive amount of air from the respiration circuit to which the endotracheal catheter is attached. More specifically, the present invention relates principally to a closed suction endotracheal catheter system that provides improved cleaning of the catheter by incorporating a wiper seal and valve arrangement that isolates the distal end of the catheter during cleaning while minimizing or eliminating air drawn from the patient""s ventilation circuit.
There are a variety of different circumstances under which a person may be required to have an artificial airway, such as an endotracheal tube, placed in his or her respiratory system. In some circumstances, such as surgery, the artificial airway""s function is primarily to keep the patient""s airway open so that adequate lung ventilation can be maintained during the procedure. In many other situations, however, the endotracheal tube will be left in the patient for a prolonged period of time. For example, with many patients, the endotracheal tube will remain in place to sustain mechanical ventilation for the life of the patient.
If an endotracheal tube is to be left in place for any substantial amount of time, it is critical that respiratory secretions be periodically removed. This is most often accomplished with the use of a respiratory suction catheter that is advanced into the endotracheal tube. As the suction catheter is withdrawn, a negative pressure is applied to the interior of the catheter to draw mucus and other secretions from the patient""s respiratory system. While a substantial amount of the mucus and other secretions will be withdrawn through the catheter, a portion of the mucus and other secretions remain on the outside of the catheter.
Because a patient""s secretions can contain infectious agents, such as streptococcus, pseudomonus, staphylococcus, and even HIV, it is important to shield clinicians from contact with the catheter. Likewise, it is important to shield patients from communicable pathogens in the environment and those that may be carried by the clinician. This is particularly important because patients on mechanical ventilation often have compromised immune systems.
In addition to concerns of cross-contamination, suctioning a patient""s artificial airway potentially interferes with proper respiration. The most common group of patients who have indwelling endotracheal tubes for prolonged periods are those who must be mechanically ventilated. Mechanically ventilated patients will typically have a fitting or manifold attached to the proximal end of the endotracheal tube (i.e., the end extending outside the patient) at an endotracheal tube hub. A pair of ventilator tubes extends from a mechanical ventilator and is typically attached to the manifold by an adapter. One tube provides inspiratory air to the patient for inhalation. The other tube allows for exhaled or expiratory air to exit the system.
Until the 1980s, it was common to disconnect the patient from the manifold and ventilator tubes each time the patient needed to be suctioned. Interference with the air supply to the patient, even if only for a few seconds, was often unnecessarily distressing to the patient. These problems were initially overcome in the invention disclosed in U.S. Pat. No. 3,991,762. The ""762 patent developed what is commonly referred to as a closed suction catheter system. In a closed suction catheter system, the catheter is maintained within a protective sleeve that is attached to the manifold. When suctioning is desired, the catheter is advanced through the manifold and into the artificial airway. Negative pressure is then applied to the catheter and secretions within the patient""s respiratory system are evacuated.
Improvements were made to the system by the invention disclosed in U.S. Pat. No. 4,569,344. This system reduces the risk of cross-contamination between the patient and the medical personnel using the device.
In the last fifteen years, there has been a significant shift toward the use of closed suction catheter systems. The advantage of closed suction catheters is that the ventilating circuit is not detached from the patient during suction procedures, as it is during open suction procedures. Because the catheter is reused a number of times over a twenty-four hour period, it is important that mucus and other secretions are cleaned from the catheter prior to periods of non-use. If the secretions are not removed the risk of auto-contamination increases. It is also important to clean the catheter to maintain suction efficiency.
There are several mechanisms by which the catheter may be cleaned. U.S. Pat. No. 4,569,344 discloses a lavage port which enables the user to inject liquid into the area surrounding the distal end of the catheter after it has been withdrawn from the patient. When liquid is injected into the closed suction catheter apparatus and suction is applied, the liquid aids in loosening and removing the secretions from the exterior of the catheter.
Unfortunately, the suction also causes an undesired amount of respiratory air to be removed through the catheter. In a xe2x80x9cclosed system,xe2x80x9d the air that is evacuated potentially disrupts the carefully controlled ventilatory cycles. Thus, the amount of respiratory air available to the patient is potentially decreased as a result of catheter cleaning. If the clinician has a difficult time cleaning secretions from the catheter, suction may be applied through the catheter several timesxe2x80x94thereby repeatedly drawing air from the ventilatory circuit.
Other closed suction, catheters have been developed to have a cleaning or lavage chamber that is physically isolated from the ventilation circuit. For example, U.S. Pat. No. 5,487,381 discloses a closed suction catheter which has a lavage chamber configured to receive the distal tip of the catheter as it is withdrawn from the manifold. A wall is then slid from an open position to a closed position to isolate the distal end of the catheter from the manifold and the ventilation circuit. A port is commonly provided to inject lavage solution into the cleaning chamber. Unfortunately, such closed suction catheters may fail to permit adequate airflow, thereby resulting in insufficient cleansing of the suction catheter. The application of negative pressure in the catheter further creates a vacuum within the chamber in the absence of sufficient airflow into the chamber. As a result, the isolated chamber inhibits free evacuation of the cleaning solution. Retention of the cleansing composition further increases the likelihood of reintroducing into the patient contaminated liquids once the chamber is opened.
In addition to the above concerns, the clinician, using commercially available closed suction catheters, is unable to adequately clean the catheter tip. If pathogens or other contaminants remain on the catheter for an extended period of time, there is increased risk of contaminating the patient. Additionally should the catheter become dried with mucus and other secretions, suction efficiency is hampered. Further, premature replacement of the closed suction catheter apparatus often occurs in light of the unsightly appearance of the dried catheters containing mucus. Thus, the need exists for a catheter apparatus capable of more effectively cleansing the distal end of the catheter without creating a substantial draw on respiratory air in the ventilation circuit.
The present invention relates to an improved respiratory suction catheter apparatus that contains a manifold and a suction catheter for use in attachment an endotracheal tube. In use, the manifold is attached to an artificial airway to form a ventilation circuit. The catheter is displaceable through the manifold and into the patient for the suctioning of secretions from the lungs. At least one seal capable of wiping a distal tip of the catheter is disposed within the manifold. This seal permits the cleansing of the catheter as the catheter is retracted from the patient and exits the manifold. The seal further minimizes the amount of air drawn from the ventilation circuit while the catheter is being cleaned. As a result, the respiratory suction catheter apparatus of the invention accomplishes the removal of mucus and other secretions from the distal tip of the catheter.
The embodiments of an improved respiratory suction catheter apparatus typically include a manifold for attachment to an artificial airway, such as an endotracheal tube, to form a ventilation circuit, a catheter which is displaceable through the manifold and into the artificial airway to suction secretions from the artificial airway and lungs, and a wiper seal and valve configuration disposed adjacent the ventilation circuit to minimize the air drawn from the ventilation circuit of a patient while the catheter is being cleaned.
In a preferred embodiment, the valve is configured to automatically engage the catheter tip after it is withdrawn through the manifold, thereby minimizing the amount of air drawn into the catheter during cleaning. Moreover, the valve may be configured to lock in a closed position when it is pulled toward the withdrawn catheter, thereby ensuring isolation of the catheter tip from the manifold.